Fabricating a semiconductor laser often involves tight confinement of carriers and waveguiding of light generated in an active region of the semiconductor. Vertical confinement and index guiding may be easily achieved by the deposition of cladding layers with the desired index of refraction, both below and above an active region of the semiconductor laser. However, lateral index guiding has proven to be more of a challenge.
In order to provide strong lateral index guiding of a laser, a higher bandgap material typically is formed laterally adjacent to the active region. In order to achieve the higher bandgap laterally adjacent regions, traditional fabrication techniques involve etching a ridge next to the active region. A higher bandgap epitaxial material is then regrown beside the ridge as described in Heterostructure Lasers Part B, H. C. Casey and M. B. Panish, Academic Press, Inc., 1978, pages 213-215, ISBN 0-12-163102-8. This etching and regrowth process is undesirable because of the high cost associated with pre-regrowth sample preparation, the epitaxial regrowth process itself, and the manufacturing logistics involved. An additional drawback is the non-planar morphology that results.
Thus a simpler method of creating a transverse index guiding mechanism that does not involve etching followed by regrowth is needed.